U.S. patent application number 14/894017 was filed with the patent office on 2016-04-28 for catheter for optical coherence tomograph, and catheter production method.
The applicant listed for this patent is SEI OPTIFRONTIER CO., LTD., SUMITOMO ELECTRIC INDUSTRIES, LTD.. Invention is credited to Junji FUKUI, Kiyotaka MURASHIMA, Ryo YAMAGUCHI.
Application Number | 20160116683 14/894017 |
Document ID | / |
Family ID | 51988889 |
Filed Date | 2016-04-28 |
United States Patent
Application |
20160116683 |
Kind Code |
A1 |
MURASHIMA; Kiyotaka ; et
al. |
April 28, 2016 |
CATHETER FOR OPTICAL COHERENCE TOMOGRAPH, AND CATHETER PRODUCTION
METHOD
Abstract
An OCT catheter and a method for manufacturing the OCT catheter,
with which the operation time, manufacturing cost, and the risk of
breakage of a spliced portion between a short-length fiber and an
optical fiber contained in an interior member can be reduced, are
provided. An OCT catheter includes an interior member that contains
an optical fiber and that is to be inserted into a body, a metal
tube that guides the interior member, and an optical connector. The
optical connector includes a ferrule assembly including a
short-length fiber and a ferrule fixed to one end of the
short-length fiber, and is connectable to a rotary joint of an OCT
system. The other end of the short-length fiber and one end of the
optical fiber contained in the interior member are fusion-spliced
together to form a spliced portion. The spliced portion is disposed
in the metal tube.
Inventors: |
MURASHIMA; Kiyotaka;
(Yokohama-shi, JP) ; YAMAGUCHI; Ryo;
(Yokohama-shi, JP) ; FUKUI; Junji; (Chigasaki-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SEI OPTIFRONTIER CO., LTD.
SUMITOMO ELECTRIC INDUSTRIES, LTD. |
Kanagawa
Osaka |
|
JP
JP |
|
|
Family ID: |
51988889 |
Appl. No.: |
14/894017 |
Filed: |
May 29, 2014 |
PCT Filed: |
May 29, 2014 |
PCT NO: |
PCT/JP2014/064255 |
371 Date: |
November 25, 2015 |
Current U.S.
Class: |
385/78 ;
65/407 |
Current CPC
Class: |
A61B 5/0066 20130101;
G02B 6/3823 20130101; A61B 5/0084 20130101; G02B 6/2551 20130101;
G02B 6/3846 20130101; G02B 6/2558 20130101; G02B 6/3624 20130101;
G02B 6/4292 20130101; G02B 6/387 20130101; G02B 6/25 20130101; G02B
6/3604 20130101; G02B 6/3825 20130101 |
International
Class: |
G02B 6/38 20060101
G02B006/38; A61B 5/00 20060101 A61B005/00; G02B 6/255 20060101
G02B006/255; G02B 6/36 20060101 G02B006/36; G02B 6/25 20060101
G02B006/25 |
Foreign Application Data
Date |
Code |
Application Number |
May 29, 2013 |
JP |
2013-113198 |
Claims
1. A method for manufacturing an optical coherence tomography
catheter including an interior member that contains a first optical
fiber and that is to be inserted into a body, and an optical
connector including a ferrule assembly, which includes a second
optical fiber and a ferrule fixed to one end of the second optical
fiber, and a tube, one end of which is directly or indirectly fixed
to the ferrule assembly and which guides the interior member, the
optical connector being connectable to a rotary joint of an optical
coherence tomography system, the method comprising: a first step of
selecting the ferrule assembly including an embedded optical fiber
having a first length as the second optical fiber, cutting the
first optical fiber so that a sum of lengths of the first optical
fiber and the second optical fiber is equal to a predetermined
length, and fusion-splicing one end of the first optical fiber and
the other end of the second optical fiber together to form a
spliced portion; and a second step of inserting the spliced portion
into the tube, wherein, when the cutting of the optical fiber or
the fusion-splicing fails in the first step, the ferrule assembly
including an embedded optical fiber having a second length, which
is greater than the first length, as the second optical fiber is
selected, the first optical fiber is cut again, and the spliced
portion is formed again.
2. An optical coherence tomography catheter comprising: an interior
member that contains a first optical fiber and that is to be
inserted into a body; an optical connector including a ferrule
assembly, which includes a second optical fiber and a ferrule fixed
to one end of the second optical fiber, and a tube, one end of
which is directly or indirectly fixed to the ferrule assembly and
which guides the interior member, the optical connector being
connectable to a rotary joint of an optical coherence tomography
system; and a spliced portion in which the other end of the second
optical fiber and one end of the first optical fiber are
fusion-spliced together, the spliced portion being disposed in the
tube.
3. The optical coherence tomography catheter according to claim 2,
wherein the optical connector includes a tubular flange member, one
end of which is fixed to the ferrule such that the second optical
fiber extends through the tubular flange member, and a tubular
joint member, h is fitted to the other end of the flange member,
wherein the tube is inserted into and fixed to the joint member at
the other end of the joint member.
4. The optical coherence tomography catheter according to claim 3,
further comprising: a tube housing that covers the interior member
and the optical connector and that is stationary when the interior
member and the optical connector rotate, wherein the tube housing
has a support disposed therein, the support supporting the interior
member or the tube, and a distance between the other end of the
joint member and the support is outside a range in which the tube
resonates when a rotational speed of the optical connector is
within an operational rotational speed range.
5. The optical coherence tomography catheter according to claim 3,
wherein an area of a cross section of a portion of the joint member
in which the tube is inserted, the cross section being
perpendicular to an axial direction of the tube, is smaller at the
other-end side of the portion of the joint member than at the
one-end side of the portion of the joint member.
6. The optical coherence tomography catheter according to claim 4,
wherein an area of a cross section of a portion of the joint member
in which the tube is inserted, the cross section being
perpendicular to an axial direction of the tube, is smaller at the
other-end side of the portion of the joint member than at the
one-end side of the portion of the joint member.
Description
TECHNICAL FIELD
[0001] The present invention relates to an optical coherence
tomography catheter and a method for manufacturing the optical
coherence tomography catheter.
BACKGROUND ART
[0002] U.S. Pat. No. 6,445,939 (Patent Document 1) discloses a
method for connecting a catheter for an optical coherence
tomography (OCT) system, which images the inside of a cavity, to a
rotary joint. An FC/APC connector is used in this method. U.S. Pat.
No. 7,813,609 (Patent Document 2) describes the structure of a
catheter for an OCT system. This catheter includes an interior
member that rotates, a tube housing that covers the interior
member, and an optical connector that provides connection to a
rotary joint.
[0003] According to the OCT catheters of the related art described
in Patent Documents 1 and 2, a method of assembling a connecting
portion to be connected to the rotary joint includes attaching a
ferrule to a proximal end of an optical fiber contained in the
interior member, and polishing an end surface of the optical fiber
at an end surface of the ferrule. The interior member is generally
expensive, and therefore needs to be processed carefully.
Therefore, the process takes a long time and the manufacturing cost
is high.
[0004] Japanese Unexamined Patent Application Publication No.
2009-205100 (Patent Document 3), Japanese Unexamined Patent
Application Publication No. 2011-118348 (Patent Document 4), and
Japanese Unexamined Patent Application Publication No. 2008-197622
(Patent Document 5) describe so-called field-installable fusion
splice single-core optical connectors. The field-installable fusion
splice single-core optical connectors can be attached to an optical
fiber in the field, and include a ferrule and a short-length fiber
fitted to the ferrule. A ferrule-side end (a front end) of the
short-length fiber is polished in advance, and a rear end of the
short-length fiber is fusion-spliced to a front end of the optical
fiber to be connected.
SUMMARY OF INVENTION
Technical Problem
[0005] An object of the present invention is to provide an OCT
catheter and a method for manufacturing the OCT catheter with which
the assembly time, manufacturing cost, and the risk of breakage of
a spliced portion between a short-length fiber and an optical fiber
contained in an interior member can be reduced.
Solution to Problem
[0006] To achieve the above-described object, a method for
manufacturing an optical coherence tomography catheter is provided.
The optical coherence tomography catheter includes an interior
member that contains a first optical fiber and that is to be
inserted into a body, and an optical connector including a ferrule
assembly, which includes a second optical fiber and a ferrule fixed
to one end of the second optical fiber, and a tube, one end of
which is directly or indirectly fixed to the ferrule assembly and
which guides the interior member, the optical connector being
connectable to a rotary joint of an optical coherence tomography
system. The method includes a first step of selecting the ferrule
assembly including an embedded optical fiber having a first length
as the second optical fiber, cutting the first optical fiber so
that a sum of lengths of the first optical fiber and the second
optical fiber is equal to a predetermined length, and
fusion-splicing one end of the first optical fiber and the other
end of the second optical fiber together to form a spliced portion;
and a second step of inserting the spliced portion into the tube.
When the cutting of the optical fiber or the fusion-splicing fails
in the first step, the ferrule assembly including an embedded
optical fiber having a second length, which is greater than the
first length, as the second optical fiber is selected, the first
optical fiber is cut again, and the spliced portion is formed
again.
[0007] According to another aspect of the present invention, an
optical coherence tomography catheter is provided. The optical
coherence tomography catheter includes (1) an interior member that
contains a first optical fiber and that is to be inserted into a
body; (2) an optical connector including a ferrule assembly, which
includes a second optical fiber and a ferrule fixed to one end of
the second optical fiber, and a tube, one end of which is directly
or indirectly fixed to the ferrule assembly and which guides the
interior member, the optical connector being connectable to a
rotary joint of an optical coherence tomography system; and (3) a
spliced portion in which the other end of the second optical fiber
and one end of the first optical fiber are fusion-spliced together,
the spliced portion being disposed in the tube.
Advantageous Effects of Invention
[0008] According to the OCT catheter and the method for
manufacturing the OCT catheter of the present invention, the
assembly time, manufacturing cost, and the risk of breakage of the
spliced portion between the short-length fiber and the optical
fiber contained in the interior member can be reduced.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a perspective view of an OCT catheter according to
an embodiment, illustrating the state in which a tube housing is
removed.
[0010] FIG. 2 is an exploded perspective view of an optical
connector.
[0011] FIG. 3 is a sectional view of the optical connector in a
longitudinal direction.
[0012] FIG. 4 is an enlarged sectional view illustrating the
detailed structures of a ferrule assembly and a joint member.
[0013] FIG. 5 is a diagram illustrating the shape of the joint
member, wherein FIG. 5(a) is a front view, FIG. 5(b) is a side
view, FIG. 5(c) is a rear view, and FIG. 5(d) is a sectional side
view.
[0014] FIG. 6 is a sectional view of the optical connector in the
longitudinal direction according to a modification.
[0015] FIG. 7 is a sectional view of the optical connector in the
longitudinal direction according to another modification.
[0016] FIG. 8 is a conceptual diagram illustrating a spliced
portion formed by fusion-splicing a proximal end of an optical
fiber contained in an interior member and the other end of a
short-length fiber.
[0017] FIG. 9 is a flowchart of a method for manufacturing the OCT
catheter.
[0018] FIG. 10 is a conceptual diagram illustrating the interior
member, a metal tube, and the ferrule assembly.
[0019] FIG. 11 is a conceptual diagram illustrating another example
of a structure for fixing the ferrule assembly to the metal tube as
a modification.
[0020] FIG. 12 is a conceptual diagram illustrating the structure
of a joint member.
[0021] FIG. 13 is a sectional view illustrating the structure of a
joint member.
DESCRIPTION OF EMBODIMENTS
[0022] The inventor of the present invention has considered
applying a field-installable fusion splice single-core optical
connector to a catheter for an OCT system. This eliminates the
necessity of a polishing step in the assembly of the catheter. In
addition, the field-installable fusion splice single-core optical
connector is inexpensive, and therefore the manufacturing cost can
be reduced. However, the method using the field-installable fusion
splice single-core optical connector involves the following
problems.
[0023] That is, OCT catheters are required to include an optical
fiber having a predetermined optical path length so that
interference waves can be observed. The allowable error of the
optical path length is, for example, as small as .+-.5 mm or .+-.2
mm. Field-installable fusion splice single-core optical connectors
include a short-length fiber having a constant length. If a spliced
portion between the short-length fiber and an optical fiber
contained in an interior member breaks, the length of the optical
fiber contained in the interior member is slightly reduced when the
optical fibers are fusion-spliced together again. Therefore, there
is a risk that the error in the optical path length will be greater
than the allowable error.
[0024] An OCT catheter and a method for manufacturing the OCT
catheter according to an embodiment of the present invention will
be described with reference to the accompanying drawings. In the
drawings, the same components are denoted by the identical
reference numerals, and redundant descriptions are omitted.
[0025] FIG. 1 is a perspective view of an OCT catheter 1A according
to an embodiment of the present invention, illustrating the state
in which a tube housing is removed. The OCT catheter 1A includes an
interior member (torque wire) 10, which is to be inserted into a
body, and an optical connector 30 to be connected to a rotary joint
of an OCT system. A lens 12, through which light is emitted toward
the inside of the body and interference light is received, is
attached to the distal end of the interior member 10. The interior
member 10 contains an optical fiber (first optical fiber) that
optically couples the optical connector 30 to the lens 12. A
proximal end portion of the interior member 10 (portion that is not
inserted into the body) is inserted into a metal tube 20, which
will be described below, at one end of the metal tube 20 and is
held in such a manner that the proximal end portion is movable in a
longitudinal direction.
[0026] FIG. 2 is an exploded perspective view of the optical
connector 30. FIG. 3 is a sectional view of the optical connector
30 in the longitudinal direction. The optical connector 30 is a
so-called fusion splice SC connector. The optical connector 30
includes a ferrule assembly 31; the metal tube 20, one end of which
is directly or indirectly fixed to the ferrule assembly 31 and
which guides the interior member 10; a joint member 32 with which
the metal tube 20 is fixed to the ferrule assembly 31; a plug
housing 33 that accommodates the ferrule assembly 31 and the joint
member 32, and an outer housing 34 that covers the plug housing 33.
The metal tube 20 guides the interior member 10 in the longitudinal
direction during, for example, a pull-back operation, and holds the
proximal end portion of the interior member 10 so that the proximal
end portion is not bent.
[0027] The ferrule assembly 31 includes a short-length fiber (also
referred to as a second optical fiber or an embedded optical fiber)
35; a substantially columnar ferrule 36 that is fixed to one end of
the short-length fiber 35 and holds the short-length fiber 35; and
a tubular metal flange member 37 that is fixed to the ferrule 36.
The ferrule 36 holds the short-length fiber 35 such that the
short-length fiber 35 extends along the center axis of the ferrule
36. An end surface (front end surface) of the ferrule 36 is
polished so as to be at an angle (for example, 8 degrees) with
respect to a plane perpendicular to the center axis of the
short-length fiber 35.
[0028] The short-length fiber 35 projects from the ferrule assembly
31 into the metal tube 20 by a predetermined length. The proximal
end surface of the optical fiber contained in the interior member
10 is fusion-spliced to the metal-tube-20-side end surface of the
short-length fiber 35. As described below, the spliced portion
between the optical fiber contained in the interior member 10 and
the short-length fiber 35 is disposed in the metal tube 20.
[0029] FIG. 4 is an enlarged sectional view illustrating the
detailed structures of the ferrule assembly 31 and the joint member
32. FIG. 5 is a diagram illustrating the shape of the joint member
32, wherein FIG. 5(a) is a front view, FIG. 5(b) is a side view,
FIG. 5(c) is a rear view, and FIG. 5(d) is a sectional side
view.
[0030] The flange member 37 has a cylindrical shape and extends in
the axial direction of the short-length fiber 35, and one end of
the flange member 37 is securely fitted to the other end portion of
the ferrule 36. The short-length fiber 35 extends through the
flange member 37. The flange member 37 includes a flange 37a that
projects in a direction that crosses the axial direction of the
short-length fiber 35. The flange 37a is brought into contact with
a projection formed on the inner wall surface of the plug housing
33, so that the ferrule assembly 31 is positioned. The inner
diameter of the flange member 37 is sufficiently greater than the
diameter of the short-length fiber 35. The gap between the flange
member 37 and the short-length fiber 35 is filled with a resin 38
that holds the short-length fiber 35. The resin 38 is composed of a
resin material such as an epoxy resin or an acrylic resin.
[0031] The joint member 32 is provided to fix the metal tube 20 to
the ferrule assembly 31. As illustrated in FIG. 5, the joint member
32 has a substantially cylindrical shape, and includes a front
portion 32a having a first inner diameter L1 on one side thereof
and a rear portion 32b having a second inner diameter L2, which is
smaller than the first inner diameter L1, on the other side
thereof. The other end portion of the flange member 37 is inserted
into the front portion 32a, so that the joint member 32 and the
flange member 37 are securely fitted together. The proximal end
portion of the metal tube 20 is inserted into the rear portion 32b.
(The rear portion 32b of the joint member 32, that is, a portion of
the joint member 32 into which the metal tube 20 is inserted, has a
constant inner diameter and a constant outer diameter. In other
words, the area of the cross section of this portion that is
perpendicular to the longitudinal direction is constant.) The
short-length fiber 35 extends through the front portion 32a and the
rear portion 32b. The joint member 32 is made of a material such as
SUS304.
[0032] The length of the joint member 32 in the axial direction of
the short-length fiber 35 is preferably such that the joint member
32 can be disposed in the plug housing 33. However, as long as the
joint member 32 is disposed in a bonding member (member that covers
the optical connector 30 that rotates at a high speed) that is
bonded to the rotary joint, the joint member 32 may have a length
such that the joint member 32 projects from the plug housing
33.
[0033] When the OCT catheter 1A is used, the optical connector 30
is rotated at a high speed. The rotating force is applied to the
interior member 10 through the metal tube 20. Depending on the
material and structure of the metal tube 20, resonance may occur at
the proper angular frequency. Therefore, the joint member 32
preferably has such a length that the resonance can be
prevented.
[0034] FIG. 6 is a sectional view of the optical connector 30 in
the longitudinal direction according to a modification. The OCT
catheter 1A further includes a tube housing 41. The tube housing 41
is a tubular body that covers the interior member 10 and the
optical connector 30. One end of the tube housing 41 is fixed to
the OCT system. Although the interior member 10 and the optical
connector 30 are rotated with respect to the OCT system, the tube
housing is stationary and does not rotate. The gap between the tube
housing 41 and the interior member 10 is filled with a liquid, such
as a physiological saline solution.
[0035] A support 42, which supports the interior member 10 or the
metal tube 20, is disposed in the tube housing 41. In many cases,
the support 42 holds the metal tube 20. In one embodiment, the
support 42 is a stop valve that prevents the above-described liquid
from flowing into the optical connector 30. To prevent the metal
tube 20 from resonating, the length of the joint member 32 is
preferably set such that the distance L between the other end 32c
of the joint member 32 and the support 42 is outside a range in
which the metal tube 20 resonates when the rotational speed of the
optical connector 30 is within an operational rotational speed
range (for example, 0 rpm to 12000 rpm).
[0036] The distance L at which the metal tube 20 resonates can be
determined as follows. That is, let L be the distance between the
other end 32c of the joint member 32 and the support 42, E be the
flexural rigidity (Young's modulus) of the metal tube 20, I be the
second moment of area of the metal tube 20, i be the order number
of the resonance, .rho. be the density of the metal tube 20, and A
be the area of cross section of the metal tube 20 that is
perpendicular to the center axis, the proper angular frequency
p.sub.i of the metal tube 20 can be determined by the following
Equation (1).
p i = ( .pi. L ) 2 EI .rho. A ( 1 ) ##EQU00001##
[0037] As the distance L increases, the resonant frequency
decreases. In Equation (1), the range of the distance L at which
the metal tube 20 resonates can be determined by substituting the
operational rotation frequency of the optical connector 30 for the
proper angular frequency p.sub.i and calculating the distance L
corresponding to the operational rotation frequency. The length of
the joint member 32 is preferably set such that the distance L is
outside the range. Since the support 42 is fixed to the tube
housing 41, the support 42 is stationary during the pull-back
operation of the interior member 10. Therefore, the distance L
changes as the joint member 32 is moved in the axial direction in
the pull-back operation. Such a change is preferably taken into
consideration when determining the range of the distance L. More
specifically, the distance of the joint member 32 is preferably
determined so that the proper angular frequency p.sub.i is greater
than or equal to 1.25 times the operational rotation frequency, in
other words, so that the operational rotation frequency is smaller
than 0.8 times the proper angular frequency. More preferably, the
metal tube 20 is made of a material that is not easily plastically
deformed (for example, SUS304) to reduce damage to the metal tube
20 caused by the resonance.
[0038] FIG. 7 is a sectional view of the optical connector 30 in
the longitudinal direction according to another modification. The
tube housing 41 includes a portion having a first inner diameter D1
and a portion (narrow portion) having a second inner diameter D2
that is smaller than the first inner diameter D1 in a region
between the other end 32c of the joint member 32 and the support
42. In this case, the narrow portion may be regarded as another
support 41a. The distance L may be determined as the distance
between the other end 32c of the joint member 32 and the support
41a.
[0039] FIG. 8 is a conceptual diagram illustrating a spliced
portion S formed by fusion-splicing the proximal end of the optical
fiber 14 (first optical fiber) contained in the interior member 10
and the other end of the short-length fiber 35 (second optical
fiber). The OCT catheter 1A further includes the spliced portion S.
The spliced portion S is disposed in the metal tube 20, and is
protected by the metal tube 20 so that breakage thereof does not
occur. Preferably, a protecting member for protecting a glass fiber
included in the optical fiber 14 and a glass fiber included in the
short-length fiber 35 is provided in a section where the glass
fibers are exposed. The protecting member may have various
structures, such as a tube fixed with an adhesive, a
heat-shrinkable tube, or a curing agent applied by using a pen or
the like.
[0040] FIG. 9 is a flowchart of a method for manufacturing the OCT
catheter 1A. In a first step S10, a plurality of ferrule assemblies
31 including short-length fibers 35 having different lengths are
prepared (step S11). Next, among the ferrule assemblies 31, a
ferrule assembly 31 including a short-length fiber 35 having a
certain length (first length) is selected (step S12). Then, the
optical fiber 14 is cut so that the sum of the lengths of the
optical fiber 14 and the short-length fiber 35 is equal to a
predetermined length, that is, an optical path length suitable for
observation of interference waves (step S13). Then, one end of the
optical fiber 14 and the other end of the short-length fiber 35 are
fusion-spliced together to form the spliced portion S (step
S14).
[0041] In the first step S10, there is a possibility that the
process of cutting the optical fiber 14 (step S13) or the fusion
splicing process (step S14) will fail (No in step S15). In such a
case, a ferrule assembly 31 including a short-length fiber 35
having a second length, which is longer than the first length, is
selected (step S12). Then, the optical fiber 14 is cut again so
that the sum of the lengths of the optical fiber 14 and the
short-length fiber 35 is equal to the predetermined length (step
S13), and the spliced portion S is formed again (step S14).
[0042] In the first step S10, the optical path length of the
optical fiber 14 and the short-length fiber 35 or the
fusion-spliced state of the spliced portion S may be inspected
(step S16). Also when the inspection result shows that the optical
path length of the optical fiber 14 and the short-length fiber 35
is outside the allowable error range or that the fusion-spliced
state is not satisfactory, a ferrule assembly 31 including a
short-length fiber 35 having the second length, which is longer
than the first length, is selected (step S12). Then, the optical
fiber 14 is cut again so that the sum of the lengths of the optical
fiber 14 and the short-length fiber 35 is equal to the
predetermined length (step S13), and the spliced portion S is
formed again (step S14).
[0043] After the first step S10, in a second step S20, the spliced
portion S is inserted into the metal tube 20, and the metal tube 20
is attached to the ferrule assembly 31 by using the joint member
32. After that, the ferrule assembly 31 is placed in the plug
housing 33, and the outer housing 34 is attached. Thus, the OCT
catheter 1A is completed.
[0044] The advantageous effects of the above-described OCT catheter
1A and the method for manufacturing the OCT catheter 1A will be
described. According to the OCT catheter 1A and the assembly method
thereof, an optical fiber having a ferrule-side end surface that is
polished in advance may be used as the short-length fiber 35, and
it is not necessary to directly polish the optical fiber 14
contained in the interior member 10. Therefore, the assembly
process can be easily carried out in a short time. In addition, a
component of an SC optical connector may be used as the ferrule
assembly 31 including the short-length fiber 35, so that the
manufacturing cost may be reduced.
[0045] In addition, in the OCT catheter 1A, the spliced portion S
is disposed in the metal tube 20. In the method for manufacturing
the OCT catheter 1A, the spliced portion S is inserted into the
metal tube 20 in the second step S20. Thus, the spliced portion S
is effectively protected by the metal tube 20, and the risk of
breakage of the spliced portion S can be reduced.
[0046] When a component of an SC optical connector is simply used
as the ferrule assembly 31, the following problem occurs. FIG. 10
is a conceptual diagram illustrating the problem, and schematically
illustrates the interior member 10, the metal tube 20, and the
ferrule assembly 31. As illustrated in FIG. 10(a), assume that the
short-length fiber 35 and the optical fiber 14 are fusion-spliced
together to form the spliced portion S. If the fusion splicing
process fails, the optical fiber 14 needs to be cut and
fusion-spliced again to the short-length fiber 35 of another
ferrule assembly 31. However, if the optical fiber 14 becomes too
short as a result of the process of cutting the optical fiber 14,
as illustrated in FIG. 10(b), the sum of the optical path lengths
of the optical fiber 14 and the short-length fiber 35 becomes
smaller than the predetermined length. Such an interior member 10
cannot be used. The interior member 10 is very expensive, and it is
preferable to avoid the situation where the interior member 10
becomes unusable. The above-described problem also occurs when the
process of cutting the optical fiber 14 fails.
[0047] Accordingly, in the manufacturing method of the present
embodiment, when the process of cutting the optical fiber 14 or the
fusion splicing process fails in the first step S10, a ferrule
assembly 31 including a longer short-length fiber 35 is selected.
Then, the optical fiber 14 is cut and the spliced portion S is
formed again. Accordingly, as illustrated in FIG. 10(c), the sum of
the optical path lengths of the optical fiber 14 and the
short-length fiber 35 may be set to the predetermined length, and
the interior member 10 can be used continuously.
[0048] In addition, in the OCT catheter 1A, the optical connector
30 includes the tubular flange member 37, one end of which is fixed
to the ferrule 36 such that the short-length fiber 35 extends
therethrough, and the tubular joint member 32, one end of which is
fitted to the other end of the flange member 37. The metal tube 20
is inserted into and fixed to the joint member 32 at the other end
of the joint member 32. Since the OCT catheter 1A is structured as
described above, the metal tube 20 can be securely fixed and does
not easily come into contact with the spliced portion S, so that
the risk of breakage of the spliced portion S can be further
reduced.
[0049] The OCT catheter 1A includes the tube housing that covers
the interior member and the optical connector and that is
stationary when the interior member and the optical connector
rotate, and a support that is attached to an inner section of the
tube housing and that supports the tube. The length of the joint
member 32 is set such that the distance L between the other end 32c
of the joint member 32 and the support 42 is outside the range in
which the metal tube 20 resonates when the rotational speed of the
optical connector 30 is within the operational rotational speed
range. Thus, vibration due to resonance of the metal tube 20 can be
prevented and burden on the subject can be reduced.
First Modification
[0050] FIG. 11 is a conceptual diagram illustrating another example
of a structure for fixing the ferrule assembly 31 to the metal tube
20 as a modification of the above-described embodiment. In this
modification, the gap between the flange member 37 and the
short-length fiber 35 is not filled with a resin, and the metal
tube 20 is inserted into and fixed to the flange member 37. One end
of the metal tube 20 is in contact with the other end surface of
the ferrule 36. Also in this case, similar to the above-described
embodiment, the assembly process can be easily carried out in a
short time. In addition, the manufacturing cost can be reduced.
Furthermore, since the spliced portion S is disposed in the metal
tube 20, the spliced portion S is effectively protected by the
metal tube 20, and the risk of breakage of the spliced portion S
can be reduced.
[0051] The flange member 37 included in the ferrule assembly 31 for
an SC connector is short, and therefore there may be a case in
which the metal tube 20 cannot be securely fixed to the flange
member 37. When the metal tube 20 cannot be securely fixed, there
is a risk that the metal tube 20 will become unstable during
high-speed rotation of the OCT catheter 1A. In such a case, the
ferrule assembly 31 and the metal tube 20 may be fixed to each
other by using the joint member 32 as in the above-described
embodiment.
Second Modification
[0052] FIG. 12 is a conceptual diagram illustrating the shape of a
joint member 43 as another modification of the above-described
embodiment. FIG. 12(a) is a sectional side view of the joint member
43, FIG. 12(b) is a sectional view taken along line XIb-XIb, and
FIG. 12(c) is a sectional view taken along line XIc-XIc. The
optical connector 30 may include the joint member 43 instead of the
joint member 32. The joint member 43 includes a rear portion 43b
into which the metal tube 20 is inserted. The area of a cross
section A2 of the rear portion 43b at the other-end side (FIG.
12(c)), the cross section A2 being perpendicular to the axial
direction of the metal tube 20, is smaller than the area of a cross
section A1 of the rear portion 43b at the one-end side (FIG.
12(b)), the cross section A1 being perpendicular to the axial
direction of the metal tube 20. More specifically, a tapered
portion 43c having an outer diameter that gradually decreases from
one end toward the other end is disposed between the one end and
the other end of the rear portion 43b. A portion 43d between the
tapered portion 43c and the one end has an outer diameter D1, and a
portion 43e between the tapered portion 43c and the other end has
an outer diameter D2 (<D1).
[0053] In the metal tube 20, stress concentration occurs and
maximum bending stress is applied at the boundary between the
portion held by the joint member and the portion that is not held
(that is, in a region near the other end of the joint member). In
this modification, the flexural rigidity of the rear portion of the
joint member decreases toward the other end, so that the stress
concentration on the metal tube 20 can be reduced and damage to the
metal tube 20 can be reduced accordingly.
[0054] The shape of the joint member according to the present
modification is not limited to that illustrated in FIG. 12. FIG. 13
is a conceptual diagram illustrating a joint member 44 having
another shape according to the present modification, and is a
sectional side view of the joint member 44 in the axial direction.
The joint member 44 includes a rear portion 44b including a tapered
portion 44c that extends to the other end of the joint member 44.
Also in this case, the effects of the present modification can be
obtained.
[0055] The OCT catheter and the method for manufacturing the OCT
catheter according to preferred embodiments of the present
invention have been described. However, the present invention is
not limited to the above-described embodiments, and various changes
may be made without departing from the scope thereof. For example,
in the above-described embodiments, the optical connector is a
fusion splice SC connector. However, the optical connector may
instead be a fusion splice connector other than the fusion splice
SC connector. In addition, although a metal tube is described as an
example of a tube that guides the interior member in the
above-described embodiments, the tube may instead be made of other
materials, such as a resin.
* * * * *